This invention relates to pneumatic telescoping cylinders and method and more particularly to a compact apparatus which is of simple construction and inexpensive and easy to manufacture and use in a variety of ways.
Prior art pneumatic actuators include the disclosure of U.S. Pat. No. 4,525,999 wherein an internal gas generator is contained in an innermost tube of the telescoping cylinder. The tubes are automatically locked in position when fully extended. Other patents illustrating the state of the art include U.S. Pat. Nos. 501,426; 2,933,070; 3,128,674; 3,136,221; 3,259,027; 3,279,755; 3,934,423; 3,973,468; 4,516,468; 4,541,325; 4,567,811; and 4,726,281.
It will be observed from the above patents that telescoping cylinders have generally been hydraulically operated because of the complexity and cost involved in the production of air operated telescoping cylinders. Prior pneumatic and hydraulic telescoping cylinders have required enclosure of the exit ports when extended, and this limits the capacity to miniaturize or minimize the length of the telescoping cylinders when in retracted position, as well as limiting the number of stages and a stroke of each stage.